Thermal cushion and device comprising such a cushion

ABSTRACT

The inventive heating cushion consists of a system of blocs ( 1 ) which comprise a thermal material, are separated by interstices ( 8 ) containing a deformable thermal material ( 10 ), are connected by joints provided with elastic solid bodies which are fixed to the blocs and form said deformable thermal material and/or elastic membranes ( 7 ) which are fixed to the blocs ( 1 ) and are tensioned for compressing a deformable body arranged in the interstices ( 8 ) and/or the joints ( 6 ) which are permeable to a fluid contained in the interstices.

FIELD OF THE INVENTION

The invention relates to thermal cushions and to their use.

STATE OF THE ART

The hospital sector and ambulatory medicine are major users of thermalcushions, in particular for external thermal regulation and in order torelieve pain or in various therapies such as for example cryotherapy.

Indeed, it is known that the application of cold can relieve pain(headaches, migraine, toothaches, muscular or inflammatory pains, etc.)or encourage the resorption of hematomas, edemas and the healing ofaccidental or surgical wounds.

U.S. Pat. No. 3,545,230 proposes a coolant cushion that uses the latentheat of fusion of a solid substance. During this fusion phase, thetemperature remains constant. The cushion comprises a layer of insolubleand hydrophilic gel in a sealed and flexible envelope. An inert andflexible substrate (for example fibres or a fabric), immersed in thegel, serves to strengthen the mechanical resistance of the cushion andallows it to take any geometrical form. To give the cushion sufficientflexibility, several layers of gel of very small thickness (barely a fewmillimetres) are superposed on each other and a flexible and inert filmis inserted between the layers of gel. This known cushion has thedrawback of being difficult and expensive to produce, its performancesare weak and its applications limited.

In document EP 0 123 949, the cryogenic substance of the cushioncomprises pieces of gel with a particular structure having an elasticitythat is comparable to that of rubber and which do not stick together atthe temperature of cold production. The motion of the pieces of gelrelative to each other in the cushion gives the latter the desiredflexibility. These known cushions nevertheless have the drawback ofrequiring an expensive gel and their manufacture is delicate and costly.

United States patent U.S. Pat. No. 3,885,403 suggests to use for thecryogenic substance a gel containing a high proportion of an agent thatlowers the freezing point below the normal temperature of use. Glycerineand propylene glycol are proposed for the agent that lowers the freezingpoint. With this known cushion, the production of cold does not resultfrom the latent heat of fusion but from the gradual reheating of thegel. This known cushion has the property that it is of simpleconstruction and retains good flexibility and suitability to flexibledeformation due to the fact that the gel does not go through a solidphase. On the other hand, it has the drawback of a short working lifesince the production of cold does not result from the latent heat offusion but from the gradual reheating of the gel. Moreover, theproductivity of the cushion (the production of cold or the extraction ofcalories per unit of time) is not constant but decreases as the gel isreheated, which represents a further drawback for this known cushion.

Document WO 97/11657 describes alveolar panels that are formed of a gridof cells filled with a thermal agent. Between the cells, the panel hasrectilinear zones with a low breakpoint that allow to divide it at will(by shearing or tension) into thermal cushions of predetermined sizesdepending on the applications for which these cushions are intended. Inthese alveolar panels, the interstices are the cause of severaldrawbacks. For one thing, they reduce the thermal capacity of the paneland for another they present an obstacle to homogeneous action of thepanel when the latter is applied onto a patient's skin.

Document FR 1 018 835 A describes thermal cushions that comprise anetwork of compartments with a thermal substance and which are connectedto each other by flexible membranes. The network of compartments isenclosed in a flexible envelope forming, together with the compartmentwalls, a chamber that is filled with a thermal fluid. These knownthermal cushions have poor flexibility and are difficult to deform,mainly when the thermal fluid of the envelope is a liquid or a solidsubstance in the state of particles. They are therefore ill-suited touniform application on a human or animal limb.

SUMMARY OF THE INVENTION

The invention aims to overcome the above-mentioned drawbacks of knownthermal cushions and to meet the needs of potential users (in particularin a hospital environment) by providing a thermal cushion of a newdesign that combines excellent flexibility/elasticity with being able toadapt perfectly, even to forms in motion and with a high and lastingcalorific value at a more or less constant temperature, whose action ishomogeneous (especially when it is used on a part of the human body),whose thickness can be maintained more of less constant during use,whose size and shape are more or less unlimited, that can undergo majorvariations in pressure without deforming and that, thanks to itsabove-mentioned properties, can adapt to many different uses, inparticular in a hospital environment, without requiring major handling.

As a result, the invention relates to a thermal cushion comprising anetwork of blocks connected by articulations and separated byinterstices, said blocks comprising a thermal substance and saidinterstices being filled, at least partially, with a deformable thermalsubstance, said thermal cushion being characterised in that thearticulations are selected from

-   -   the elastic solid bodies that are attached to the blocks and        thus form at least part of the above-mentioned deformable        thermal substance;    -   the elastic membranes that are attached to the blocks and put        under pressure so that they compress a deformable body present        in the interstices, said deformable body thus forming at least        part of the deformable thermal substance; and    -   the articulations, which are permeable to a fluid present in the        interstices, said fluid thus forming at least part of the        deformable thermal substance.

The thermal cushion according to the invention is intended to be broughtinto contact with a physical body with the aim of affecting the heatexchanges of this body with the surrounding environment.

The expression “body” is to be understood in a general sense asreferring to a material object. It refers without distinction to asolid, liquid or gaseous body. In the case of a solid body, it may forexample be the surface of a solid object or a part of the anatomy of ananimal or of a human being. In the case of a liquid body, it may be thesurface of a table of a liquid bath. In this application of theinvention, the cushion may for instance act as a sealed partitionbetween two different liquids or between a liquid and a surroundingatmosphere, for example the environment. In the case of a gaseous body,it comprises an atmosphere. In this application of the invention, thecushion according to the invention may for instance form a screenbetween two different atmospheres, for example a hot atmosphere (theatmosphere of an industrial furnace) and an atmosphere at moderatetemperature. As a variant, in the case of a liquid or gaseous body, itmay possibly be enclosed in a sealed envelope, for example a flexiblemembrane.

The ambient environment may be a gaseous or liquid environment. In thecase of a gaseous environment, it may for instance be atmospheric air,the atmosphere of a heated room, the atmosphere of a refrigerated room(for example a cool store) or the atmosphere of an industrial furnace(non-exhaustive list). In the case where the surrounding environment isa liquid environment, it may for instance be water or an industrialchemical bath.

In the present document, the expression “normal temperature of use”refers to the temperature of the thermal substance of the blocks and/orthe interstices when the cushion is used.

In the present document, the term “cushion” refers in a very generalsense to any solid and flexible element intended to be brought intocontact with the body (as defined above) so as to cover it at leastpartially or to wrap it entirely or partially. The thermal cushionaccording to the invention can therefore be adapted in very varied waysdepending on the use it is intended for. It may for example take theform of an article of bedding (pillow, cover, mattress), a pocket, asleeve, an article of clothing or part of an article of clothing, apackaging, a screen or curtain, a covering (non-exhaustive list). It maybe made in various modules that can be assembled.

The thermal cushion according to the invention is a cushion which, whenit is brought into contact with a body (as in the above definition), atnormal temperature of use, causes a transfer of heat between saidcushion and said body or contributes to maintaining the temperature ofsaid body more or less constant.

The thermal cushion according to the invention is termed “calorificcushion” or “cryogenic cushion” when its normal temperature of use isdifferent from that of the body with which it is brought into contact,so that a heat transfer occurs between said cushion and said body. Whenthe heat transfer is occurring naturally in the direction from the bodytowards the thermal cushion, it is a cryogenic cushion. In the case whenthe heat transfer occurs in the direction from the thermal cushion tothe body, the thermal cushion according to the invention is a calorificcushion.

The thermal cushion according to the invention is termed “isothermiccushion” when its normal temperature of use is more or less equal tothat of the body with which it is brought into contact so that there isno heat transfer between said body and the thermal cushion. Anisothermic cushion according to the invention then provides thetechnical function of a calorific insulator by forming an obstacle tothe heat transfer between the body and the ambient environment.

The thermal cushion according to the invention comprises a network ofblocks between which interstices are provided. The interstices aregenerally connected to each other.

By definition, each block of the cushion is a solid element. The shapeof the blocks of the cushion according to the invention will be detailedlater on.

The blocks are assembled in a network. They are moreover spaced so as toform a network of interstices between them. The cushion according to theinvention thus comprises an interwoven structure of interstices in aninterwoven structure of blocks. The network of blocks generallycomprises a single layer or stratum of blocks although a network formedby several layers of superposed blocks is not excluded from theinvention.

The blocks of the network are articulated with each other. In otherwords, the blocks of the network are connected to each other byarticulations. Details concerning the articulations will be providedlater on.

In the cushion according to the invention, the shapes and sizes of theblocks, the shapes and sizes of the interstices and the choice of thearticulations are adapted so that the network of blocks forms a solidstructure that is deformable by bending and/or twisting and/or rotationaround multiple axes distributed in a three-dimensional space. Thisparticular feature of the cushion according to the invention allows itto easily adapt to virtually any shape of body to which it is applied(for example part of the human or animal anatomy) and to follow itsmovement.

In the cushion according to the invention, the blocks and theinterstices comprise a thermal substance. The thermal substance will beexplained later on.

The shapes of the blocks depend on the use of the cushion and are notcritical to the definition of the invention. The blocks may for examplehave a spherical, hemispherical, ovoid, annular, lenticular, conical,truncated conical or polyhedral shape. The blocks may have flat, curvedor skewed faces, for example helicoidal, or may comprise an assembly offlat faces and of curved or skewed faces. They may for instance have theshape of little barrels that combine a curved annular face and flatfaces at the ends. In general, any shape is acceptable which, associatedwith the interstices and articulations connecting the blocks, allows thedeformation of the cushion as explained above. Polyhedral shapes aregenerally preferred.

Among the polyhedral shapes, right-angled or pyramidal polyhedrons arepreferred. Truncated pyramids are especially recommended. Amongright-angled or pyramidal polyhedrons, polyhedrons with triangular,trapezoidal, square, rectangular or octagonal bases are preferred.

In a preferred embodiment of the invention, each block is formed by twotruncated pyramids joined along their long bases, for example twotriangular, trapezoidal, square or octagonal truncated pyramids. In thispreferred embodiment of the invention, the blocks are advantageouslyarticulated in the geometrical plane of the above-mentioned long basesof the two truncated pyramids.

As explained above, the interstices arranged between the blocks have thefunction of allowing the motion of these blocks around the articulationsthat connect them. The shapes of the interstices will depend on variousparameters such as the type of deformation desired for the network ofblocks (single-axis, double-axis or triple-axis bending, twisting,stretching or combination of two or several of these deformation types),the degree of deformation, the shapes and sizes of the blocks, thearticulations used and the arrangement of the articulations between theblocks.

In the thermal cushion according to the invention, the blocks are madeof a thermal substance. The thermal substance of the blocks gives itsthermal properties to the thermal cushion according to the invention. Inthe case of a cryogenic cushion, the thermal substance of the blocks isselected from those which, once brought to normal temperature of use andthen subjected to cooling, release a large quantity of heat. In the caseof a calorific cushion, the thermal substance of the blocks is selectedfrom those which, once brought to normal temperature of use and thenheated, pick up a large quantity of heat. In the case of an isothermiccushion, the thermal substance of the blocks is selected from thosewhich block the heat transfer or which, once brought to normaltemperature of use, then require a large input of heat in order tochange their temperatures. Thermal substances which, at normaltemperature of use, have a high specific heat are generally suitable forthe three types of cushion according to the invention. These thermalsubstances are those known and used in technology for their property ofaccumulating large quantities of heat and which are found in particularin applications as thermal accumulators.

In the thermal cushion according to the invention, blocks may beentirely made of the thermal substance which is then necessarily solidat normal temperature of use as well as in normal conditions of handlingfor the thermal cushion. As a variant, blocks may, in addition to thethermal substance, comprise another substance which does not on its ownperform the function of the thermal substance as defined above. Thethermal substance may be identical in all the blocks or may differdepending from the block. Moreover, each block may comprise a singlethermal substance or a mixture of two or several thermal substances. Inthe present document, the expression “thermal substance” refers withoutdistinction to a single thermal substance or to a mixture of differentthermal substances.

In one particular embodiment of the thermal cushion according to theinvention, the blocks comprise cells inside which the thermal substanceis held. This embodiment of the thermal cushion according to theinvention is especially well suited to the case where the thermalsubstance of the blocks is not solid at normal temperature of use or innormal conditions of handling for the thermal cushion. In thisembodiment of the cushion according to the invention, the outer shape ofthe cells must meet the above-mentioned shape requirements with regardto the blocks. The choice of the substance for the cells is determinedby the need for said cells to be chemically inert relative to thethermal substance that they comprise and relative to the chemical andthermal environment during their normal use. The cells must also havemechanical properties that are compatible with the mechanical stressesto which the cushion is normally subjected at normal temperature of useor in the course of handling and they must be more or less incapable ofdeformation (they must be made of a rigid or semi-rigid material and ofa suitable shape). In this particular case, each cell may be entirelyisolated from the neighbouring cells or, as a variant, the cells may bein contact with each other so as to allow the fluid content of saidcells to circulate between them. In the case where the thermal substanceof the cushion is liquid or gaseous, the walls of the cells are usuallyimpermeable to liquids or gases. Plastic materials are generallysuitable for making up the cells. Useful plastic materials includepolyolefins, in particular polymers and copolymers of ethylene andpropylene, chlorinated polymers, especially vinyl chloride andvinylidene chloride polymers and copolymers,styrene-ethylene-butyl-styrene copolymers and polyurethane.Polyethylene, polypropylene, vinyl polychloride andstyrene-ethylene-butyl-styrene copolymers are suitable in mostapplications. As a variant, the cells may also be made of metal, forexample by drawing sheets of malleable metal or alloy such as aluminiumand aluminium alloys. According to another variant, the cells or some ofthem are formed from composite materials: one part of the cell is madeof one material and another part of the cell is made of anothermaterial. According to an additional variant, one part of the network ofcells is made of one material and another part of the network of cellsis made of another material.

Any known forming method may be used to produce the network of cells.The methods of casting, pressing, drawing and injection are suitable.

According to a suitable method, a corrugated sheet of a plastic or metalmaterial is formed, which thus has a network of holes or half-cells.Another sheet is then glued or welded onto the corrugated sheet so as toblock the holes of the corrugated sheet and to form the cells. Thisother sheet may be a corrugated or a flat sheet.

In one preferred embodiment of the invention, the thermal substance ofthe blocks comprises a substance that undergoes a change of state atnormal temperature of use. In this embodiment of the invention, theexpression “change of state” is considered in its general sense andcovers any physical and/or chemical change of the substance, occurringat a more or less constant temperature and characterised in the latentheat of the change of state. Depending on the substance used, the changeof state may in particular comprise the fusion of a solid,solidification of a liquid, vaporisation of a liquid, condensation of agas, total or partial hydration of a salt, total or partial dehydrationof a salt, crystallisation of an amorphous solid or recrystallisation ofan allotropic form of a crystal into another allotropic form. In thisembodiment of the invention, the thermal substance of the blocks may beentirely made of said substance that undergoes a change of state atnormal temperature of use. As a variant, the thermal substance of theblocks may also comprise other substances or materials that do notundergo a change of state at normal temperature of use. Then, in orderto avoid overburdening the text to no purpose, it will be assumed thatit is the entire thermal substance that undergoes a change of state atnormal temperature of use. It is in any event clearly understood that,as explained above, the invention does not exclude the case in whichonly a part of the thermal substance of the blocks undergoes a change ofstate (in the event, when it is made of a mixture of several chemicalcompounds of which only one undergoes a change of state at normaltemperature of use or when an additional material is incorporated whichis not involved in the thermal function of the thermal cushion, forexample a magnet).

In the above-defined preferred embodiment, the change of state undergoneby the thermal substance of the blocks at normal temperature of usecorresponds to a heat absorption by said material in the case of acryogenic cushion and to the emission of heat in the case of a calorificcushion. In the case of an isothermic cushion, the change of stateundergone by the thermal substance of the blocks at normal temperatureof use corresponds to a heat absorption by said thermal substance whensaid normal temperature of use (which is also that of the body for whichthe cushion is intended) is lower than that of the surroundingenvironment. The change of state corresponds to an emission of heat bythe thermal substance when the normal temperature of use is higher thanthat of the surrounding environment.

In order to use a thermal cushion true to the preferred embodiment thathas just been described, the state of the thermal substance of theblocks should be suitably selected. In the case where the cushion isused as a cryogenic cushion, it is necessary first of all to bring thethermal substance of the blocks to a state which, at normal temperatureof use, will undergo a change of state corresponding to a heatabsorption (for example the fusion of a solid or the vaporisation of aliquid). In the case where the cushion is used as a calorific cushion,it is first necessary to bring the thermal substance of the blocks to astate which, at normal temperature of use, will undergo a change ofstate corresponding to a heat production (for example the solidificationor crystallisation of a liquid or the condensation of a gas). In thecase where the cushion is used as an isothermic cushion, in asurrounding environment at a temperature that is higher than the normaltemperature of use, it is first necessary to bring the thermal substanceof the blocks to a state which, at normal temperature of use, willundergo a change of state corresponding to a heat absorption (forexample the fusion of a solid or the vaporisation of a liquid). In thecase where the cushion is used as an isothermic cushion, in asurrounding environment at a temperature that is lower than the normaltemperature of use, it is first necessary to bring the thermal substanceof the cells to a state which, at normal temperature of use, willundergo a change of state corresponding to a heat production (forexample the solidification or crystallisation of a liquid or thecondensation of a gas). Moreover, all other things being equal in thepreferred embodiment that has just been described, the best results areobtained with thermal substances which, at normal temperature of use,have a high latent heat of change of state.

In the preferred embodiment that has just been described, the thermalsubstance of the blocks undergoing a change of state at normaltemperature of use may be a pure body. As a variant, it may be achemical composition that is congruent to said normal temperature of useso that the change of state occurs at a more or less constanttemperature.

In the preferred above-described embodiment and its implementationvariants, the choice of thermal substance for the blocks depends on thenormal temperature of use of the cushion. This is itself dependent onthe application for which the thermal cushion is intended. Water andaqueous solutions are normally suitable in the particular case of acryogenic cushion intended for therapeutic applications. Pure water issuitable in the case of applications where the normal temperature of useof the cushion is close to 273K (0° C.). For applications where thenormal temperature of use is lower than 273K, aqueous solutions arerecommended in which the dissolved body and its concentration areselected depending on the normal temperature of use of the cryogeniccushion. It is recommended that the dissolved body and its concentrationare selected in such a way that partial or total precipitation of saiddissolved body is avoided at the normal temperature of use of thecushion. Examples of dissolved bodies include sodium chloride, calciumchloride, sodium carbonate, propylene glycol, glycerine, ethyl alcoholand propyl alcohol.

As explained above, when the thermal substance of the blocks is liquid,it is enclosed in cells whose walls are generally impermeable toliquids. When a liquid thermal substance that undergoes vaporisation atnormal temperature of use is used, it may turn out advantageous to use,for the cells, walls with oriented permeability or walls that areimpermeable to the liquid phase of the thermal substance but permeableto its gaseous phase (for example impermeable/breathable PU). However,the invention is not limited to this embodiment and it also covers thecase where the walls of the cells are impermeable to the liquid phaseand to the gaseous phase of the thermal substance of the cells.

In the thermal cushion according to the invention, the thermal substanceof the blocks forms the main active element of the cushion and gives itits thermal properties (cryogenic, calorific or isothermic properties,depending on the intended use).

The thermal substance of the interstices has the function of increasingthe effectiveness of the cushion by increasing its active surface andits active volume. The thermal substance of the interstices must havethermal properties that are analogous to those mentioned above for thethermal substance of the blocks. Its thermal properties must thereforebe adapted to the intended purpose of the cushion, to its normaltemperature of use, to the temperature of the body for which the cushionis intended and to the ambient temperature. As regards the thermalproperties of the thermal substance of the interstices, what wasexplained above for the thermal substance of the blocks may therefore berepeated.

The thermal substance of the interstices must also be deformable. Thisadditional property of the thermal substance of the interstices isnecessary to allow the movement of the articulated blocks and thedeformation of the cushion. The choice of the thermal substance of theinterstices and/or its implementation are therefore dependent on thestructural parameters of the cushion such as the shape of the blocks,the shape of the interstices separating the blocks, the articulations ofthe blocks and the positions of these articulations in the network ofthe blocks.

In a particular embodiment of the thermal cushion according to theinvention, the thermal substance of the interstices comprises anelastic, solid body. This may for example comprise foam in syntheticpolymer or an elastomer, for example a natural or synthetic rubber. Inthe case of foam, it may be of a type with open pores or of a type withclosed pores. In the case of foam with closed pores, these pores may befilled by a gas with a coefficient of heat transmission that is lowerthan that of air, for example nitrogen or argon.

In another embodiment of the thermal cushion according to the invention,the thermal substance of the interstices comprises a fluid. The fluidmay comprise a liquid, a gas, a gel (or viscous fluid) or a solid in theform of crumbly particles (for example a powder). In this embodiment ofthe invention, the interstices must be sealed so as to retain thethermal substance. The sealing means used should not be an obstacle tothe movement of the blocks on their articulations. Additionalinformation concerning the sealing means of the interstices will beprovided later on.

In the thermal cushion according to the invention, the interstices maybe partially or completely filled by the thermal substance. It ispreferable for the interstices of the network of blocks to be completelyfilled with the thermal substance.

Depending on the applications for which the thermal cushion according tothe invention is intended, substances capable of reflecting infraredradiation or ultraviolet radiation may possibly be incorporated into thethermal substances of the blocks and the interstices and/or, whererelevant, to the membranes or envelopes. Examples of such reflectivesubstances include in particular aluminium powders. Similarly, for otherparticular applications, substances capable of absorbing infraredradiation such as for instance carbon powder may be advantageouslyincorporated into the thermal substances and/or, where relevant, intothe membranes or envelopes.

In the thermal cushion according to the invention, the intersticesbetween the blocks may be open. This embodiment of the invention issuitable when the deformable thermal substance of the interstices is adeformable solid (for example foam) at normal temperature of use and innormal handling conditions for the thermal cushion. Alternatively theinterstices between the blocks may be sealed by a sealing means. Thisalternative is necessary in the case where the thermal substance of theinterstices is a fluid (as defined above) in normal conditions of useand of handling for the thermal cushion. It is also suitable in the casewhere the thermal substance of the interstices is a deformable solidbody. As mentioned above, it is appropriate to choose a sealing meansthat does not form an obstacle to the movement of the articulatedblocks.

The thermal cushion according to the invention is characterised by thedesign of the articulations of the blocks. It is characterised inparticular by an original selection of said articulations, associated toa selection of the thermal substance of the interstices, so that thenetwork of blocks may undergo deformations in the three spatialdimensions, by stretching, twisting and rotation.

As a result, according to a first implementation of the invention, thearticulations of the blocks comprise elastic solid bodies that areattached to the blocks and therefore constitute at least a part of thethermal substance of the interstices. Information concerning the elasticsolid body was given above.

In this first implementation of the invention, the attachment of theelastic solid body to the blocks may be achieved by any appropriatemeans, for example gluing, welding or by means of screws or pegs(non-exhaustive list).

In a second implementation of the invention, the articulations of theblocks comprise elastic membranes that are attached to the blocks andput under tension in such a way as to compress a deformable body,present in the interstices, said deformable body thus forming at least apart of the deformable thermal substance. The deformable body may be anelastic solid body or a fluid. In the case of a fluid, it may be anincompressible fluid or a compressible fluid. Information concerning theelastic solid bodies and the fluids was given above.

In this implementation of the invention, each interstice may be coveredby an individual membrane. The membranes are therefore appropriatelyattached to the blocks so as to allow them to be put under tension. Anyappropriate means may be used, for example gluing or welding. Theattachment of the membranes to the blocks must be sealed when thethermal substance of the interstices is fluid (gas or liquid). In aparticular variant of the above-mentioned second implementation of theinvention, an impermeable and elastic sheet covers at least a part of orthe entire network of blocks and it therefore substitutes for theindividual membranes sealing the interstices. In another particularvariant of the above-mentioned second implementation of the invention,the network of blocks is enclosed in a sealed and elastic envelope. Inthis other variant, the envelope may be appropriately attached to theblocks in order to block the interstices so that they are sealed whenthe thermal substance or the interstices is fluid (gas or liquid). Inthe case where the thermal substance of the interstices is a deformablesolid (for example foam or elastomer), the envelope may equally beattached to all the blocks in the network of blocks, to some of them(and not to others) or not be attached to any block. The attachment ofthe envelope to the blocks may be achieved by any appropriate means.Appropriate means include gluing and welding. The envelope may be simpleor it may comprise a complex film or it may comprise several layerslinked to each other or not. It may be of different compositiondepending on each face. It may have treatments and additives that giveit specific active properties depending on the use. It may compriseintake/outlet tubes for the introduction or the circulation of thethermal substance of the interstices when it is a fluid.

In a third implementation of the invention, the interstices between theblocks comprise a fluid and the articulations are permeable to saidfluid. In this implementation of the invention, the fluid may comprise aliquid, a gas, a gel or a solid in the form of crumbly particles (forexample a powder) and it forms at least a part of the deformable thermalsubstance of the interstices. Information concerning the fluid of theinterstices was given above. In this third implementation of theinvention, the selection of the articulations will depend on the stateof the fluid present in the interstices. Said articulations may forexample comprise flexible membranes (possibly elastic) that are porousto gases or liquids, flexible and perforated partitions, lattices,hinges with perforations or any other articulation not likely to hinderthe free circulation of the fluid present in the interstices.

Depending on the type of deformable thermal substance present in theinterstices, the cushion according to the invention may associateseveral types of articulation, for example elastic solid bodies attachedto the blocks, pivots and membranes. As a variant, in additional to thearticulations, the blocks of the network may be linked to each other byrigid lugs whose mechanical resistance to bending is low and controlled.In this variant of the invention, the rigid lugs serve to give rigidityto the cushion and to make it easier to handle and-they break when thecushion is applied to the body and deformed.

The thermal cushion according to the invention has the advantageousproperty of combining excellent heat storage and thermal exchangeproperties with excellent flexibility/elasticity that allows it toimmediately adapt to the form of a physical body to which it is beingapplied in such a way that it perfectly fits the form of this body andtherefore ensures homogeneous regulation of the temperature or of theheat exchanges over the whole covered surface of said body. Due to thedesign and structure of the thermal cushion according to the invention,its thickness has no effect on its flexibility and its ability to bedeformed. In other words, the invention allows to adapt the thickness ofthe cushion to the desired thermal properties (to its thermal capacity)without adversely affecting its flexibility or its ability to easilyadapt to various body shapes.

In another particular embodiment of the thermal cushion according to theinvention, the network of blocks bears, on at least a part of itssurface, a sealed and elastic envelope, generally provided with a devicefor the intake and outlet of a fluid (for example a gas). In thisembodiment of the invention, the envelope is intended to be brought intocontact with the above-mentioned physical body, with which a heatexchange must occur. By introducing a defined volume of a suitable fluid(normally air) into the envelope, it is possible to control the heattransfer between the thermal cushion and the physical body.

In the thermal cushion according to the invention, the network of blocksmay be arranged in a single layer. As a variant, the network of blocksmay be formed by the superposition of several layers. The layer or theassembly of layers may advantageously be held as a sandwich between twosealed and elastic envelopes, usually being each provided with an intakeand outlet device for a fluid (for example a gas). In this embodiment ofthe invention, one of the envelopes therefore serves, by resting on anappropriate support (for example a bandage or a shell), to apply thethermal cushion onto the body with a defined pressure. The otherenvelope serves to control the heat transfer between the thermalsubstances and the body, as explained above.

The thermal cushion according to the invention has numerousapplications. It can be used in particular as an isothermic cushion (orthermostat) to maintain the temperature of containers such as bottles orthermostatic flasks. Such use of the thermal cushion according to theinvention has applications in the industry for maintaining chemicalproducts at predefined temperatures as well as in the food sector forheating, cooling and maintaining the temperature of chambers for foodproducts.

The thermal cushion according to the invention also has applications asa cryogenic cushion, in particular in the chemical or pharmaceuticalindustry for keeping chemical products at low temperatures as well as inthe food industry for preserving food products.

Because of its form-fitting and deformable nature, the thermal cushionis particularly suitable for applications associated with wellbeing bothin the form of articles of clothing and various healthcare articles (forexample compresses, masks, massage tools).

Because of its excellent ability to deformation, the thermal cushionaccording to the invention is especially adapted to medical, paramedicaland sports applications, in particular for thermal regulation andcryotherapy. Cryotherapy is a medical technique that is widely used,especially for relieving pain (for example headaches, migraines,toothaches, muscular or inflammatory pains) so as to aid the resorptionof hematomas or edemas and the healing of accidental or surgical wounds.

The invention therefore also relates to a device comprising a thermalcushion according to the invention for the therapeutic treatment ofhuman or animal bodies.

In the device according to the invention, the cushion and its network ofblocks are adapted to the method of treatment or depending on the partof the human or animal body for which said device is intended.

In a particular embodiment of the device according to the invention, thecushion is placed inside a rigid shell. In this embodiment of the deviceaccording to the invention, the shell is normally adapted to the part ofthe human or animal body to which the thermal cushion must be applied.It has, for example, the form of an elbow, a knee, a finger, a foot or askull.

In this embodiment of the device according to the invention, the shellmay be formed of two or several articulated elements to make it easierto put it on the human or animal body. This embodiment of the deviceaccording to the invention is especially recommended if the device isintended to be applied to the head of a person or of an animal.

In an advantageous variant of the embodiment that has just beendescribed, a sealed and elastic envelope is inserted between the shelland the network of blocks of the cushion and this envelope is usuallyprovided with an intake and outlet device for a fluid. This variant ofthe invention achieves homogeneous application of the thermal cushionover the human and animal body. It also allows the application of thethermal cushion to the human or animal body with a defined pressure,regulated by the pressure of the fluid allowed into the envelope.

In another variant of the embodiment described above, a panel isarticulated to the shell and sized in such a way that it can form,together with the shell, a hermetic chamber comprising the thermalcushion. In this variant of the device according to the invention, thethermal cushion and the shell form an integral part of a hermetic caseused for handling the device. By using a panel that is suitablyinsulated, the device thus designed allows to maintain predeterminedthermal properties. In this way, the device is especially well suitedfor use in the case of an emergency outside of a hospital, for exampleon the public highway. In the above-mentioned variant of the deviceaccording to the invention, the shell and the articulated panel may beprovided with medical instrumentation with for example thermometers ortensiometers. It may also be provided with an independent device forgenerating heat or cold during the handling of the device, in particularduring its transportation or storage.

The invention also relates to a thermal wall comprising an assembly ofthermal cushions according to the invention, between two partitions orbetween a partition and a body. The thermal wall may be a calorificwall, a cryogenic wall or an isostatic wall, depending on whether thethermal cushions collected between its two partitions are calorificcushions, cryogenic cushions or isostatic cushions.

The thermal wall according to the invention may for example form thewall of a thermos.

In the thermal wall according to the invention, thermal cushions arepreferably used in which the network of blocks is arranged in anenvelope filled with a deformable thermal substance. At least a part ofthe thermal substance of the envelope may comprise the thermal substanceof the interstices.

SHORT DESCRIPTION OF THE FIGURES

Special features and details of the invention will be made clearer inthe following description of the attached figures which show someparticular embodiments of the invention.

FIG. 1 is a schematic view in cross-section of a particular embodimentof the thermal cushion according to the invention;

FIG. 2 shows a perspective view, with partial cutaway, of a detail ofthe thermal cushion of FIG. 1;

FIG. 3 shows a detailed perspective view of FIG. 2;

FIG. 4 shows, in horizontal section, another embodiment of the thermalcushion according to the invention;

FIG. 5 shows the thermal cushion of FIG. 4 in vertical section;

FIG. 6 shows a perspective view of a particular embodiment of the deviceaccording to the invention;

FIG. 7 is a side view, with partial cutaway, of another embodiment ofthe device according to the invention;

FIG. 8 is a back view of the device of FIG. 7;

FIG. 9 is a sketch, in cross-section, of a third embodiment of thedevice according to the invention;

FIG. 10 shows in vertical cross-section a thermal wall according to theinvention;

FIG. 11 shows a thermal cushion according to the invention that can beused in the thermal wall of FIG. 10; and

FIG. 12 shows another thermal cushion according to the invention thatcan be used in the thermal wall of FIG. 10.

The figures are not drawn to scale.

The same reference numbers generally refer to the same elements.

DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS

The thermal cushion shown in FIG. 1 and 2 comprises a network of blocks1, formed by hollow cells. The blocks or cells 1 have the shape ofprisms with square bases. Each cell 1 is formed by two truncatedpyramids 3 and 4, attached along their long square bases. The sideridges of the two truncated pyramids have bevelled edges (2). Thenetwork of cells 1 is formed by the assembly of two corrugated sheets 5in a flexible polymer material (for example in plastified polyvinylchloride or in styrene-ethylene-butyl-styrene copolymer) pre-drawn andwelded to each other along tongues 6 between the cells (a corrugatedsheet 5 is shown in FIG. 3). The tongues 6 are flexible and elastic andthey act as articulations between the cells 1. They are pierced byapertures 9 whose function will be explained later on. By bending ortwisting the assembly of sheets 5, the cushion of cells may thus adoptcomplex profiles to fit an appropriate body, for example part of theanatomy of a human being or of an animal.

The thermal cushion of FIG. 1 to 3 is a cryogenic cushion intended foruse in cryotherapy. To this end, the cells 1 are filled with a suitablethermal substance whose definition was given above. The thermalsubstance is advantageously an aqueous solution with a freezing pointthat is congruent and occurs at a temperature corresponding to thetemperature at which the cushion is intended (normal temperature ofuse). When the normal temperature of use is close to 273K (or 0° C.),the aqueous solution may be replaced by distilled or mineral water.

The interstices 8 defined between the cells 1 and the tongues 6 arefilled with a deformable thermal substance 10 (shown in FIG. 1 only).The thermal substance 10 shown in FIG. 1 is an elastic solid body, forexample a solid mass made of elastomer or polymer foam. It is preferablyselected so as to have a high specific heat at normal temperature ofuse.

A flexible and elastic envelope 7 surrounds the network of cells 1 andinterstices 8. The elastic envelope 7 is for instance a film ofstyrene-ethylene-butyl-styrene copolymer.

Before using the thermal cushion of FIG. 1 to 3 in a therapeuticapplication, it is maintained, for instance in a cool store, at atemperature low enough to freeze the aqueous solution of the cells 1.The thermal cushion is taken out of the cool store when it is about tobe used and it can be immediately applied to a part of the human bodythat is to be subjected to cryogenic therapy, for example a hand, thehead or an arm. Due to the flexibility of the envelope 7 and tongues 6and to the elasticity of the thermal substance 10 contained in theinterstices 8, the cushion deforms and perfectly adapts to themorphology of the human body.

In a modified embodiment of the thermal cushion of FIG. 1 to 3, theelastic envelope 7 is welded to the cells 1 and put under tension sothat the elastic solid body 10 of the interstices 8 is maintained in astate of elastic compression in these interstices 8.

When the thermal cushion shown in FIG. 1 to 3 is used for a medicaltherapy, a compress can be inserted between the thermal cushion and theanatomical part of the human body. Any compress usually used in medicaltherapy is suitable. It may for example comprise a gauze. After thethermal cushion is placed on the compress, it is firmly attached to thepart of the body to be treated by means of a bandage (adhesive orotherwise) so that when it deforms, it perfectly fits the entire part ofthe body to be treated. As a variant, the cushion may itself be providedwith medical adhesive parts of a repositionable type. In this particularcase, the bandage is not required.

In order to improve the thermal action of the cushion on the anatomicalpart treated, a second thermal cushion may be advantageously placed onthe first thermal cushion. In this case, only the first thermal cushion[the one directly applied to the human body (or to the compress)] is putin the cool store, the other thermal cushion being maintained at ambienttemperature. In this application, the second thermal cushion may act asa thermal insulator. It may in particular act as an insulating bandagefor attachment and/or compression. It may be provided with an inflatablepocket for optimum application to concave body forms.

In some embodiments, the cushion may combine in a single item thethermal function and the function of an insulating bandage and maycomprise the above-mentioned compress that is inserted between thethermal cushion and the anatomical part of the human body.

In a modified embodiment of the thermal cushion of FIG. 1 to 3, thetongues 6 are pierced by apertures 9 (whose function will be explainedlater) and the thermal substance 10 of the interstices 8 is in a liquidor gel state at normal temperature of use. In this embodiment of thecushion, the envelope 7 is attached to the cells 1 so as to hermeticallyseal the interstices 8. The apertures 9 have the function of allowingthe circulation of the fluid thermal substance in the network ofinterstices 8 when the cushion is subjected to deformation.

The structure of the thermal cushion possibly allows its use bycirculation of fluid in the interstices and/or cells (connected byfilling/circulation channels).

Reactions of thermogenic/cryogenic mixtures may be used to initiate thethermal function independently or to extend the duration of the actionwithout requiring the cushion to be removed and recharged.

The cushion may comprise elements for the control and regulation of thetemperature.

In the embodiment shown in FIG. 4 and 5, the cushion comprises a networkof cells 1 between which a network of an elastic solid mass 10 isinserted. The elastic solid mass 10 is for example a solid mass ofelastomer or a foam of polymer resin. The elastic network 10 is attachedto the network of cells 1 by gluing or welding. The elastic network 10also acts as an articulation between the cells 1.

FIG. 6 shows the use of the thermal cushion according to the inventionin a device for the therapeutic treatment of an element of the humanbody. The therapeutic treatment may for example be the cryogenictreatment of an arm or a thigh. To this end, the device comprises athermal cushion referred to in its entirety by the reference number 11.The thermal cushion comprises, as explained above, a network of blocks 1and interstices 8, comprising suitable thermal substances. The thermalcushion 11 is attached to a bandage 12 intended to attach it to aperson's arm. A rectangular aperture 13 is made in the network of blocks8. The aperture 13 serves to give access to a defined area of the arm inorder to subject it to a suitable therapeutic treatment (for example totreat a wound, a contusion or another local condition there). Theaperture 13 may be used to apply a dressing to the arm. As a variant, itmay be filled by a small removable thermal cushion according to theinvention. The thermal cushion 11 of the device of FIG. 6 may forexample be a cryogenic cushion, designed to put an arm into hypothermiawhile the zone accessible through the aperture is subjected to asuitable therapeutic treatment.

The device of FIG. 6 may obviously be adapted to the treatment of thelimb of an animal, for example a horse's leg.

FIG. 7 and 8 show a device according to the invention for thetherapeutic treatment of a person's skull. The device comprises a rigidshell 14 that takes the form of a helmet closely fitting the person'shead 15 and neck. The helmet 14 is made up of three articulated elements16, 17 and 18 (FIG. 8). Element 16 serves to cover the top of the skulland elements 17 and 18 are intended to surround the neck. The inner partof the helmet 14 is shown at a larger scale in a zone marked by thereference X in FIG. 7. It comprises a thermal cushion under the shell14. The thermal cushion is true to the invention and successivelycomprises an insulating layer 19, a sealed envelope 20 (whose functionwill be explained later on), a network 11 of articulated blockscomprising a thermal substance and a second sealed envelope 22. Thesealed envelope 20 comprises a device (not shown) for injecting a fluidunder pressure into it. This is usually air that is injected into thepocket by means of an electric or manual pump (of the type used forbicycles or used on medical or paramedical tensiometers). The pocket 22is similar to the pocket 20 and is also designed for injecting a definedvolume of air under pressure. When it is necessary to subject apatient's head to cryogenic treatment, for example to put it intohypothermia, the helmet 14 and its thermal cushion are maintained in acool store for an appropriate period so that they reach a predeterminedtemperature. Element 16 of the helmet 14 is then applied to the top ofthe skull on the patient's head 15 and elements 17 and 18 are foldedaround the patient's neck. A defined volume of air is then injected intothe pocket 20 so as to apply the network of articulated blocks 11 with apredetermined pressure onto the patient's head 15. Then, a definedvolume of air is possibly injected into the pocket 22. The air pocket 22acts to form an insulating film between the network of blocks 11 and thehead 15 so as to regulate the heat flux between the head 15 and thethermal substance of the blocks 11 of the thermal cushion. The heat fluxis controlled at will by choosing an appropriate volume of air to beinjected into the pocket 22. The shell 14 of the device of FIG. 7 and 8may advantageously be provided with medical tools with for examplethermometers or tensiometers.

FIG. 9 shows a variant of the embodiment of the device of FIG. 7 and 8.In the device of FIG. 9, the shell 14 has the shape of a hemisphereadapted to cover the top of a person's skull. It is made up of twoelements 23 and 24 articulated on a ring 25 intended to surround thecranium at the level of the forehead. The elements 23 and 24 each have athermal cushion according to the invention (not shown) on their innerfaces. Two panels 26 and 27 are moreover articulated to the ring 25. Thetwo panels 26 and 27 form, together with the elements 23 and 24, achamber in which the thermal cushions of elements 23 and 24 areenclosed. The shell 14 and its thermal cushions thus form an integralpart of a case (which may be hermetic and insulating) for thetransportation and handling of the device. The device shown in FIG. 9 isespecially well suited for emergency use outside of a hospital, forexample to attend an emergency on the public highway. The shell 14 mayalso be provided with an independent device for generating heat or coldduring the transportation of the device or its handling.

FIG. 10 shows another application of the thermal cushion according tothe invention. It shows part of a cryogenic wall 28 of a thermosintended to preserve organs or cold foodstuffs. The cryogenic wall 28comprises a pair of partitions 29 and 30 that define between them achamber filled with small cryogenic cushions 31 according to theinvention. In accordance with the invention, each cryogenic cushion 31comprises blocks 32 (FIG. 11) connected by a flexible membrane 33 andfilled with a rigid cryogenic substance, for example ice. The network ofblocks 32 is enclosed in a flexible and hermetic envelope 34 filled witha fluid cryogenic substance 35. The fluid cryogenic substance 35 may forexample be a gel. The deformable nature of the cryogenic substance 35optimises the refrigerant properties of the wall 28.

FIG. 12 shows another embodiment of the cryogenic cushions 31 that canbe used in the cryogenic wall 28 of FIG. 10. In this embodiment, thecryogenic cushion comprises a chain of blocks 32 connected by pivots 33and comprising a rigid cryogenic substance (for example ice). The chainof blocks 32 is enclosed in a tubular envelope 34 filled with acryogenic gel 35.

By extension, the invention also relates to thermal walls in which thethermal cushions comprise a single block 32 (comprising a rigid thermalsubstance) in a flexible envelope comprising a fluid thermal substance[liquid, gas, gel or in the state of crumbly particles (powder)].

1. Thermal cushion comprising a network of blocks connected byarticulations and separated by interstices, said blocks comprising athermal substance and said interstices being filled, at least partially,with a deformable thermal substance, characterised in that thearticulations are selected from the elastic solid bodies that areattached to the blocks (1) and thus form at least part of theabove-mentioned deformable thermal substance; the elastic membranes (7)that are attached to the blocks (1) and put under tension so as tocompress a deformable body present in the interstices (8), saiddeformable body forming at least part of the deformable thermalsubstance; and the articulations (6) that are permeable to a fluidpresent in the interstices (8), said fluid thus forming at least part ofthe deformable thermal substance.
 2. Cushion according to claim 1,characterised in that, in the case where the deformable thermalsubstance of the interstices (8) comprise an elastic solid body, thelatter comprises a foam and/or an elastomer.
 3. Cushion according toclaim 1 characterised in that the permeable articulations compriseperforated, flexible and/or elastic membranes (9).
 4. Cushion accordingto claim 1 characterised in that a flexible and/or elastic sheet (7)wraps the blocks (1).
 5. Cushion according to claim 1 characterised inthat the shape of the blocks (1) is selected from spherical,hemispherical, ovoid, annular, lenticular, conical, truncated conicaland polyhedral shapes.
 6. Cushion according to claim 5, characterised inthat the blocks (1) are polyhedrons with a triangular, trapezoidal,square or octagonal base.
 7. Cushion according to claim 6, characterisedin that each block (1) is formed by two truncated pyramids (3, 4) joinedalong their long bases and in that the blocks are articulated on aarticulation (6) positioned in the geometrical plane of said long base.8. Cushion according to claim 1 characterised in that the blocks (1)comprise cells with the thermal substance.
 9. Cushion according to claim8, characterised in that, in the case where the thermal substance of theblocks (1) is in a liquid or gaseous state, the cells are sealedrelative to the state of the thermal substance.
 10. Cushion according toclaim 1 characterised in that at least one of the thermal substancescomprises a substance that is subjected to a change of state at normaltemperature of use.
 11. Cushion according to claim 10, characterised inthat the above-mentioned substance is a pure body or a chemical compoundthat is congruent at normal temperature of use.
 12. Cushion according toclaim 1 characterised in that the network of blocks (11) is covered by asealed and elastic envelope (20 or 22) provided with an intake andoutlet device for a fluid.
 13. Cushion according to claim 1characterised in that an aperture (13) is made in the network of blocks(11).
 14. Cushion according to claim 13, characterised in that theaperture (13) comprises another, removable network of blocks. 15.Cushion according to claim 1 characterised in that the blocks of thenetwork are articulated in a single layer.
 16. Cushion according toclaim 15, characterised in that the layer is maintained in a sandwichbetween two sealed and elastic envelopes (20,22), being each providedwith a device for the intake and outlet of a fluid.
 17. Cushionaccording to claim 1 characterised in that the blocks of the network arearranged in at least two layers.
 18. Cushion according to claim 17,characterised in that the two layers are maintained in a sandwichbetween two sealed and elastic envelopes, being each provided with adevice for the intake and outlet of a fluid.
 19. Cushion according toclaim 1 characterised in that the network of blocks is arranged in anenvelope filled with a deformable thermal substance.
 20. Cushionaccording to claim 19, characterised in that at least part of thethermal substance of the envelope comprises the thermal substance of theinterstices.
 21. Device comprising a thermal cushion according to claim1 for the therapeutic treatment of a human or animal body.
 22. Deviceaccording to claim 21, characterised in that the cushion (11) is placedinside a rigid shell (14).
 23. Device according to claim 22,characterised in that the rigid shell (14) takes the shape of a humanskull (15).
 24. Device according to claim 22 characterised in that asealed and elastic envelope (20) is inserted between the network ofblocks (11) and the shell (14), said envelope being provided with adevice for the intake and outlet of a fluid.
 25. Device according toclaim 22 characterised in that the shell (14) comprises at least twoarticulated elements (16,17,18).
 26. Device according to claim 22characterised in that at least one panel (26,27) is articulated to theshell (14) and sized so as to form, together with the shell, a chamberthat is more or less hermetic and comprises the cushion.
 27. Deviceaccording to claim 26, characterised in that the shell (14) and/or apanel (26,27) comprises medical tools.
 28. Thermal wall comprising anassembly of thermal cushions (31) according to claim 19 between twopartitions (29,30).